This application is also related to U.S. Pat. No. 5,428,606, xe2x80x9cDigital Information Commodities Exchangexe2x80x9d, issued on Jun. 27, 1995, which is incorporated herein by reference.
The present invention relates to digital watermarks.
Digital watermarks exist at a convergence point where creators and publishers of digitized multimedia content demand localized, secured identification and authentication of that content. Because existence of piracy is clearly a disincentive to the digital distribution of copyrighted works, establishment of responsibility for copies and derivative copies of such works is invaluable. In considering the various forms of multimedia content, whether xe2x80x9cmaster,xe2x80x9d stereo, NTSC video, audio tape or compact disc, tolerance of quality degradation will vary with individuals and affect the underlying commercial and aesthetic value of the content. It is desirable to tie copyrights, ownership rights, purchaser information or some combination of these and related data to the content in such a manner that the content must undergo damage, and therefore a reduction in value, with subsequent, unauthorized distribution of the content, whether it be commercial or otherwise.
Legal recognition and attitude shifts, which recognize the importance of digital watermarks as a necessary component of commercially distributed content (audio, video, game, etc.), will further the development of acceptable parameters for the exchange of such content by the various parties engaged in the commercial distribution of digital content. These parties may include artists, engineers, studios, INTERNET access providers, publishers, agents, on-line service providers, aggregators of content for various forms of delivery, on-line retailers, individuals and parties that participate in the transfer of funds to arbitrate the actual delivery of content to intended parties.
Since the characteristics of digital recordings vary widely, it is a worthwhile goal to provide tools to describe an optimized envelope of parameters for inserting, protecting and detecting digital watermarks in a given digitized sample (audio, video, virtual reality, etc.) stream. The optimization techniques described hereinafter make unauthorized removal of digital watermarks containing these parameters a significantly costly operation in terms of the absolute given projected economic gain from undetected commercial distribution. The optimization techniques, at the least, require significant damage to the content signal, as to make the unauthorized copy commercially worthless, if the digital watermark is removed, absent the use of extremely expensive tools.
Presumably, the commercial value of some works will dictate some level of piracy not detectable in practice and deemed xe2x80x9creasonablexe2x80x9d by rights holders given the overall economic return. For example, there will always be fake $100 bills, LEVI jeans, and GUCCI bags, given the sizes of the overall markets and potential economic returns for pirates in these marketsxe2x80x94as there also will be unauthorized copies of works of music, operating systems (Windows95, etc.), video and future multimedia goods.
However, what differentiates the xe2x80x9cdigital marketplacexe2x80x9d from the physical marketplace is the absence of any scheme that establishes responsibility and trust in the authenticity of goods. For physical products, corporations and governments mark the goods and monitor manufacturing capacity and sales to estimate loss from piracy. There also exist reinforcing mechanisms, including legal, electronic, and informational campaigns to better educate consumers.
The present invention relates to implementations of digital watermarks that are optimally suited to particular transmission, distribution and storage mediums given the nature of digitally-sampled audio, video, and other multimedia works.
The present invention also relates to adapting watermark application parameters to the individual characteristics of a given digital sample stream.
The present invention additionally relates to the implementation of digital watermarks that are feature-based. That is, a system where watermark information is not carried in individual samples, but is carried in the relationships between multiple samples, such as in a waveform shape. The present invention envisions natural extensions for digital watermarks that may also separate frequencies (color or audio), channels in 3D while utilizing discreteness in feature-based encoding only known to those with pseudo-random keys (i.e., cryptographic keys) or possibly tools to access such information, which may one day exist on a quantum level.
The present invention additionally relates to a method for obtaining more optimal models to design watermark systems that are tamper-resistant given the number and breadth of existent digitized-sample options with differing frequency and time components (audio, video, pictures, multimedia, virtual reality, etc.).
To accomplish these goals, the present invention maintains the highest quality of a given content signal as it was mastered, with its watermarks suitably hidden, taking into account usage of digital filters and error correction presently concerned solely with the quality of content signals.
The present invention additionally preserves quality of underlying content signals, while using methods for quantifying this quality to identify and highlight advantageous locations for the insertion of digital watermarks.
The present invention integrates the watermark, an information signal, as closely as possible to the content signal, at a maximal level, to force degradation of the content signal when attempts are made to remove the watermarks.
The present invention relates to a method for amplitude independent encoding of digital watermark information in a signal including steps of determining in the signal a sample window having a minimum and a maximum, determining a quantization interval of the sample window, normalizing the sample window, normalizing the sample window to provide normalized samples, analyzing the normalized samples, comparing the normalized samples to message bits, adjusting the quantization level of the sample window to correspond to the message bit when a bit conflicts with the quantization level and de-normalizing the analyzed samples.
The present invention also relates to a method for amplitude independent decoding of digital watermark information in a signal including steps of determining in the signal a sample window having a minimum and a maximum, determining a quantization interval of the sample window, normalizing the sample window to provide samples, and analyzing the quantization level of the samples to determine a message bit value.
The present invention additionally relates to a method of encoding and decoding watermarks in a signal where, rather than individual samples, insertion and detection of abstract signal features to carry watermark information in the signal is-done.
The present invention also relates to a method for pre-analyzing a digital signal for encoding digital watermarks using an optimal digital filter in which it is determined what noise elements in the digital signal will be removed by the optimal digital filter based on response characteristics of the filter.
The present invention also relates to a method of error coding watermark message certificates using cross-interleaved codes which use error codes of high redundancy, including codes with Hamming distances of greater than or equal to xe2x80x9cnxe2x80x9d, wherein xe2x80x9cnxe2x80x9d is a number of bits in a message block.
The present invention additionally relates to a method of preprocessing a watermark message certificate including a step of determining an absolute bit length of the watermark message as it will be encoded watermark pseudo-random key bits using a non-linear (chaotic) generator or to a method of mapping pseudo-random key and processing state information to affect an encode/decode map using a non-linear (chaotic) generator.
The present invention additionally relates to a method of guaranteeing watermark certificate uniqueness including a step of attaching a time stamp or user identification dependent hash or message digest of watermark certificate data to the certificate.
The present invention also relates to a method of generating and quantizing a local noise signal to contain watermark information where the noise signal is a function of at least one variable which depends on key and processing state information.
The present invention also relates to a method of dithering watermark quantizations such that the dither changes an absolute quantization value, but does not change a quantization level or information carried in the quantization.
The present invention further relates to a method of encoding watermarks including inverting at least one watermark bit stream and encoding a watermark including the inverted watermark bit stream.
The present invention also relates to a method of decoding watermarks by considering an original watermark synchronization marker, an inverted watermark synchronization marker, and inverted watermarks, and decoding based on those considerations.
The present invention also relates to a method of encoding and decoding watermarks in a signal using a spread spectrum technique to encode or decode where information is encoded or decoded at audible levels and randomized over both frequency and time.
The present invention additionally relates to a method of analyzing composite digitized signals for watermarks including obtaining a composite signal, obtaining an unwatermarked sample signal, time aligning the unwatermarked sample signal to the composite signal, gain adjusting the time aligned unwatermarked sample signal to the composite signal, estimating a pre-composite signal using the composite signal and the gain adjusted unwatermarked sample signal, estimating a watermarked sample signal by subtracting the estimated pre-composite signal for the composite signal, and scanning the estimated watermark sample signal for watermarks.
The present invention additionally relates to a method for varying watermark encode/decode algorithms automatically during the encoding or decoding of a watermark including steps of (a) assigning a list of desired CODECs to a list of corresponding signal characteristics which indicate use of particular CODECs, (b) during encoding/decoding, analyzing characteristics of the current sample frame in the signal stream, prior to delivering the frame to CODEC, (c) looking up the corresponding CODEC from the list of CODECs in step (a) which matches the observed signal characteristics from step (b), (d) loading and/or preparing the desired CODEC, (e) passing the sample frame to the CODEC selected in step (c), and f) receiving the output samples from step (e).
The present invention also relates to a method for varying watermark encode/decode algorithms automatically during the encoding or decoding of a watermark, including steps of (a) assigning a list of desired CODECs to a list of index values which correspond to values computed to values computed as a function of the pseudo-random watermark key and the state of the processing framework, (b) during encoding/decoding, computing the pseudo-random key index value for the current sample frame in the signal stream, prior to delivering the frame to a CODEC, (c) looking up the corresponding CODEC from the list of CODECs in step (a) which matches the index value from step (b), (d) loading and/or preparing the desired CODEC, (e) passing the sample frame to the CODEC selected in step (c), and (f) receiving the output samples from step (e).